Currently, with the rapid development of projection display technology, there is a trend for the projection display products to have reduced size and enhanced brightness. A light source for the projection display is an essential component of the projection display product. Conventionally, the projection display product generally uses trichromatic light emitting diodes (LEDs) as its light source, where each of the trichromatic LEDs emits light independently. Since the independently emitted light beams are of the three primary colors having different wavelengths, the independently emitted light beams are performed with two respective beam combination operations so as to ultimately output desired white light. As a beam combining lens is required for each of the beam combination operations, it is generally necessary to provide at least two beam combining lenses in the conventional light source for projection display.